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1/^ Qocn BUREAU OF MINES 

IU y^OU INFORMATION CIRCULAR/1990 



£S5 



Analysis of Dump-Point Accidents 
Involving Mobile Mining 
Equipment 



By J. P. May 




#+*m* \ UmSm BUREAU OF MINES 



3 
O 

years ,%* THE MINERALS SOURCE 



80 



**4U OF ^ 



1910-1990 



Mission: As the Nation's principal conservation 
agency, the Department of the Interior has respon- 
sibility for most of our nationally-owned public 
lands and natural and cultural resources. This 
includes fostering wise use of our land and water 
resources, protecting our fish and wildlife, pre- 
serving the environmental and cultural values of 
our national parks and historical places, and pro- 
viding for the enjoyment of life through outdoor 
recreation. The Departmentassessesourenergy 
and mineral resources and works to assure that 
their development is in the best interests of all 
our people. The Department also promotes the 
goals of the Take Pride in America campaign by 
encouraging stewardship and citizen responsibil- 
ity for the public lands and promoting citizen par- 
ticipation in their care. The Department also has 
a major responsibility for American Indian reser- 
vation communities and for people who live in 
Island Territories under U.S. Administration. 



Information Circular 9250 

Analysis of Dump-Point Accidents 
Involving Mobile Mining 
Equipment 

By J. P. May 



UNITED STATES DEPARTMENT OF THE INTERIOR 
Manuel Lujan, Jr., Secretary 

BUREAU OF MINES 
T S Ary, Director 






/ 



A 



°\ 



■> 






o 



o 



c- 




Library of Congress Cataloging in Publication Data: 



May, J. P. (James P.) 

Analysis of dump-point accidents 
May. 


involving mobile mining 


equipment / by J. P. 


p. cm. - (Bureau of Mines information circular; 9250) 






Includes bibliographical references. 






Supt. of Docs, no.: I 28.27:9250. 








1. Mine haulage-Accidents. 2. 
Information circular (United States. 


Stockpiles-Accidents. 
Bureau of Mines); 9250. 


[. Title. 


II. Series: 


TN295.U4 [TN331] 


622 s-dc20 [622'.8] 




89-600364 
CIP 



CONTENTS 

Page 

Abstract 1 

Introduction 2 

Definitions 2 

Scope of problem 3 

Surface mobile mining equipment accidents as a percentage of all surface mining accidents 3 

Dump-point accidents as a percentage of surface mobile mining equipment accidents 3 

Summary of problem 4 

Frequency and severity of dump-point accidents, by equipment type 4 

Analysis of dump-point accidents involving haulage trucks 4 

General 4 

Industry affected 6 

Dump-point structures 6 

Dump-point construction materials 6 

Equipment specifications 7 

Operator-related factors 7 

Age 7 

Job experience 7 

Mine experience 9 

Drug and alcohol abuse 9 

Seatbelt use 10 

Primary accident causes 10 

Loading out at the toe 12 

Backing over edge 12 

Slope failure 12 

Backing through berm 13 

Dumping incorrect area 13 

Mechanical 13 

Undetermined 13 

Contributing factors 14 

Construction method 14 

Truck orientation 14 

Dumpbed position 14 

Truck motion 14 

Analysis of dump-point accidents involving front-end loaders 14 

Analysis of dump-point accidents involving dozers 15 

Analysis of dump-point accidents involving scrapers 16 

MSHA regulations pertaining to dump-point safety 16 

Summary 16 

Bibliography 17 

Appendix— Code of Federal Regulations excerpts pertaining to operation of mobile equipment 

on stockpiles and waste dumps 18 

ILLUSTRATIONS 

1. Percentage of dump-point accidents by equipment type 5 

2. Percentage of dump-point fatalities and lost workdays by equipment type 5 

3. Percentage of dump-point accidents involving a haulage truck, by industry 7 

4. Number of haulage trucks involved in dump-point accidents, by capacity 8 

5. Percentage of total dump-point accidents involving a haulage truck, by age group 8 

6. Number of dump-point accidents involving a haulage truck, by years of job experience 9 

7. Primary dump-point accident causes involving haulage trucks 11 



TABLES 

Page 

1. Surface mining, surface mobile mining equipment, and dump-point accident data, 1983-87 3 

2. Dump-point accident data by equipment type, 1983-87 4 

3. Dump-point accidents involving a haulage truck, by commodity 6 

4. Structures involved in dump-point accidents, 1983-87 6 

5. Dump-point construction materials involved in haulage truck accidents, by industry 7 

6. Dump-point accidents involving a haulage truck, by years of mine experience 10 

7. Summary of data corresponding to use of seatbelts 10 

8. Primary accident causes and contributing factors for 82 dump-point accidents 11 

9. Summary of haulage truck dump-point accidents involving slope failure 13 

10. Summary of occurrence and severity of dump-point accidents involving front-end loaders 15 

11. Summary of occurrence and severity of dump-point accidents involving dozers 15 



UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT 


ft 


foot 


pet 


percent 


lb 


pound 


St 


short ton 



ANALYSIS OF DUMP-POINT ACCIDENTS INVOLVING 
MOBILE MINING EQUIPMENT 



By J. P. May 1 



ABSTRACT 

This U.S. Bureau of Mines report identifies and evaluates factors responsible for dump-point accidents 
involving mobile mining equipment. Information regarding the occurrence and severity of the accidents, 
the industries affected, the types of equipment involved, the primary and contributing causes, and 
pertinent Federal regulations is included. The aim of this report is to provide information that will aid 
mine operators in the recognition of hazards associated with mobile equipment operation near the dump 
points of stockpiles and waste dumps. 



'Mining engineer, Twin Cities Research Center, U.S. Bureau of Mines, Minneapolis, MN. 



INTRODUCTION 



Dump-point accidents occur in all of the major mineral 
industries including coal, metal, nonmetal, crushed stone, 
and sand and gravel. These industries, either through the 
construction of temporary material stockpiles or construc- 
tion of semipermanent to permanent waste or spoil piles, 
utilize large mobile mining equipment in elevated areas 
near dump points. Almost without exception, the dump- 
point accident involves the fall of such equipment over the 
edge and down the front slope of the stockpile or waste 
dump. The types of mining equipment involved in these 
stockpile accidents include front-end loaders, dozers, scrap- 
ers, and various sizes of haulage trucks from 20-st-capacity 
units for highway use to 170-st-capacity mine haulage 
trucks (dumpers) designed for off-highway use. 

Accidents involving dump points were analyzed for the 
1983-87 period. It was felt that a 5-year period would be 
large enough to present a representative sample of acci- 
dents, yet would keep the amount of data at a level that 
could be reasonably managed. The most recent 5-year 
period for which data were available was chosen to provide 
the best representation of current mining methods and 
technology. 

All data utilized in the analysis were gathered from an 
accident data base maintained by the Bureau. The com- 
puterized data base, known as ADA (accident data anal- 
ysis), is based on accident and injury report data files 
gathered by the Safety and Health Technology Center 
(SHTC) in Denver, CO, a branch of the Mine Safety and 
Health Administration (MS HA). These data files include 
all coal and metal-nonmetal accidents reported by mining 
operations dating back to the early 1970's. 



A mine operator is required to submit a report for each 
accident or occupational injury meeting the criteria in title 
30, part 50, of the Code of Federal Regulations (CFR). 
Based on accident severity, the operator may also be re- 
quired to contact MSHA immediately. MSHA officials 
will make a determination if a more thorough investigation 
is necessary. By MSHA's definition of an accident and 
occupational injury, reporting is only required for those 
dump-point accidents that caused death or that had a 
reasonable potential to cause death, that resulted in lost 
work time, that required medical treatment, or that re- 
stricted an individual from performing his or her normal 
duties. 

For the purpose of the analysis in this report, only those 
accidents that met MSHA reporting criteria were studied, 
not all dump-point accidents that occurred. In addition to 
SHTC narratives, original mine reports and any available 
investigation reports for each specific accident were ob- 
tained. All information gathered was reviewed by three 
project members. The data were then organized and clas- 
sified, providing the structure for the analysis of accidents 
in this report. 

This report is organized into two primary sections. The 
first section analyzes the effect of dump-point accidents on 
the mining industry. The second section provides a de- 
tailed analysis of dump-point accidents for each equipment 
type. The majority of the second section emphasizes haul- 
age trucks and includes a less descriptive and more gener- 
alized analysis for front-end loaders, dozers, and scrapers. 
A review and discussion of MSHA regulations pertaining 
to dump-point safety is also provided. 



DEFINITIONS 



The following are definitions of selected terms used in 
this report: 

Berm.-A pile or mound of material used to prevent 
travel of mobile mining equipment over the edge of a 
bank; normally used along the edge of haulroads and the 
crests of stockpiles. 

Dump Point— The, active area of a stockpile, waste 
dump, or spoil pile where material is placed during con- 
struction of the pile; normally at the edge or crest of the 
pile. 

Haulage 7racfc.-Self-propelled wheeled machine, having 
an open body, which transports and dumps or spreads 
material. Loading is performed by means external to the 
truck. The term "haulage truck" is used in lieu of the 
International Organization for Standardization (ISO) term 
"dumper" because haulage truck is a more familiar term to 
U.S. mining industries. 

Lost-Workday Accident (LWA) -Injury resulting in the 
inability to perform all job duties on any day after the 
injury. 



Mobile Mining Equipment. -Tracked or rubber-tired 
equipment which by its nature is mobile. For the pur- 
pose of this report it means earth-moving equipment used 
around surface stockpiles; specifically, haulage trucks, 
front-end loaders, dozers, and scrapers. 

MSHA. -Mine Safety and Health Administration, regu- 
latory and enforcement branch of the U.S. Department of 
Labor responsible for maintenance of mine safety through 
enforcement of Federal mine laws and technical and train- 
ing assistance to mine operations. 

Spoil Pile— A structure consisting of unconsolidated 
overburden materials removed during surface coal mining 
operations. 

Stockpile.- An accumulation of ore or mineral formed 
to create a reserve to feed a processing plant or for direct 
shipment. 

Surge Pile.-S\rm\ds to a stockpile only usually smaller 
and more temporary in nature. 

Waste Dump. -A mine waste structure or dump. An 
accumulation of non-ore-bearing waste material removed 
for development of an ore body. 



SCOPE OF PROBLEM 



The purpose of this section is to develop an under- 
standing of the impact of dump-point accidents on the 
mining industry. The scope of the problem will be brought 
into perspective through analysis and comparison of pro- 
gressively narrowing accident categories, eventually fo- 
cusing on the subcategory of dump-point accidents. This 
will be accomplished through the comparison of the fre- 
quency and severity of all surface mining accidents, 2 all 
surface mobile mining equipment accidents, and finally all 
dump-point accidents. A breakdown of dump-point acci- 
dents by equipment type will also be provided. 

SURFACE MOBILE MINING EQUIPMENT 
ACCIDENTS AS A PERCENTAGE OF 
ALL SURFACE MINING ACCIDENTS 

Surface mobile mining equipment accidents are more 
severe than the average surface mining accident and are 
responsible for a disproportionate share of the total fa- 
talities and lost workdays. Table 1 provides a summary 
tabulation of accident data for all surface-mining-related 
accidents for the 1983-87 period. It also shows the fre- 
quency of accidents involving surface mining mobile 
equipment and those involving mobile equipment at dump 
points. A comparison of mobile mining equipment acci- 
dents as a percentage of all surface-mining-related acci- 
dents, and a comparison of dump-point accidents as a 
percentage of all mobile mining equipment accidents is 
also provided. 

The potential for an accident resulting in a serious 
injury is greater for the operator of a piece of mobile 
mining equipment than the average surface miner. While 
mobile mining equipment accidents are only responsible 
for 8 pet of the total surface accidents they result in 27 pet 



T'br this report, surface mining accidents include all those accidents 
categorized by MSHA as surface at underground, strip-open pit, surface 
auger, culm bank-refuse, dredge mining, and other surface. They do 
not include accidents categorized by MSHA as underground, 
independent shops-yards, preparation plants, and offices. 



of the fatalities and 11 pet of the total lost workdays. This 
can be attributed to the size and complexity of the equip- 
ment involved and the ever changing mine environment. 
The mine environment changes to reflect the natural pro- 
gression of development that occurs in a mining operation 
as well as the effect of external factors such as weather. 
In addition many of the older mining operations, which 
were originally designed for small equipment, have up- 
dated to larger equipment without corresponding changes 
in mine layout and facilities. 

Safe operation of mobile equipment is extremely de- 
pendent on the capabilities of the operator. The ability 
of an operator to identify and react correctly and quickly 
to a potential hazard that may develop is more critical for 
mobile equipment operation than for most mining tasks. 
The dynamic environment of mobile equipment operation 
and nature of the job thus provide a greater potential for 
a hazardous situation to develop and a serious injury to 
occur. 

DUMP-POINT ACCIDENTS AS A PERCENTAGE 

OF SURFACE MOBILE MINING 

EQUIPMENT ACCIDENTS 

Accidents involving the operation of mobile equipment 
near the dump point of stockpiles and waste dumps are 
significant in their impact on the total number of fatalities 
and lost workdays experienced by mobile equipment oper- 
ators (table 1). 

A dump-point accident is more severe in nature than an 
average mobile equipment accident. A dump-point LWA 
results in an average loss of 67.0 days from work versus an 
average loss of 36.9 days from work for all other surface 
mobile mining equipment accidents, and is responsible for 
a disproportionate share of the fatalities. The severity of 
dump-point accidents can be attributed to the extreme 
nature of an accident where a large piece of mobile equip- 
ment falls over a high embankment. More specific param- 
eters relating to dump-point accidents will be discussed in 
the "Primary Accident Causes" section. 



Table 1. -Surface mining, surface mobile mining equipment, and dump-point accident data, 1983-87 1 

Category Accidents Fatalities Lost-workday Lost 

accidents workdays 

All surface 35,042 252 21,162 646,758 

Mobile equipment: 

Total 2,805 67 1,845 70,522 

Portion of all surface pet . . 8 27 9 11 

Dump point: 

Total 103 11 72 4,821 

Portion of mobile equipment ... pet . . 4 16 4 7_ 

'Mobile equipment and dump-point accidents were not considered in the surface category; dump-point accidents were 
not considered in the mobile equipment category. 



SUMMARY OF PROBLEM 

Accidents involving the operation of mobile equipment 
near the dump point of stockpiles and waste dumps ac- 
count for 0.3 pet of all surface-mining-related accidents. 

Although the frequency of reportable dump-point acci- 
dents is relatively low, the severity of the accidents is high, 
resulting in a substantial impact on the mining industry. 
Of the dump-point accidents reported to MSHA, 10.7 pet 
resulted in a fatality compared to only 2.1 pet for mobile- 
equipment-related accidents and 0.57 pet for all other 



surface-mining-related accidents. This high frequency rate 
resulted in dump-point accidents being responsible for 
4.37 pet of all surface-mining-related fatalities, which is a 
significant percentage of the total. The severity of dump- 
point accidents is also reflected in the average number of 
days off for each LWA. Each dump-point LWA results in 
an average of 67.0 days lost from work. This compares to 
an average of only 36.9 days for mobile-equipment-related 
accidents and 29.8 days for all other surface-mining-related 
accidents. 



FREQUENCY AND SEVERITY OF DUMP-POINT ACCIDENTS, 

BY EQUIPMENT TYPE 



Haulage trucks were responsible for 80 pet of all the 
dump-point accidents that occurred in the 5-year period 
studied. A breakdown on the percentage of dump-point 
accidents by equipment type is shown in figure 1. As 
would be expected, haulage trucks are also responsible for 
a significant majority of both the total fatalities and the 
total lost workdays experienced. This is demonstrated in 
figure 2 where the percentage of dump-point fatalities and 
lost workdays is given by equipment type. 

Haulage trucks show a slightly lower frequency of fa- 
talities and higher percentage of lost workdays than the 
percentage of total accidents would indicate. Conversely 
dozers and front-end loaders show a higher frequency of 
fatalities and lower percentage of lost workdays than the 
percentage of total accidents would indicate. This would 
indicate that although infrequent, dozer and front-end 
loader dump-point accidents involving a fall down a slope 



have a lower potential for operator survivability than haul- 
age truck or scraper accidents. Scraper dump-point acci- 
dents, although extremely infrequent, do demonstrate a 
high degree of severity. Although no fatalities were re- 
corded, they did result in 8.0 pet of the total lost workdays. 
A summary of dump-point accident data by mobile equip- 
ment type is provided in table 2. 

The remainder of this report will emphasize the causes 
of dump-point accidents and specific parameters affecting 
their occurrence. From the preceding discussion and a 
review of table 2, it is obvious that the primary impact on 
the mining industry results from dump-point accidents 
involving haulage trucks. For this reason, the majority of 
the remainder of this report will emphasize dump-point 
accidents involving haulage trucks. A final brief discussion 
of accidents involving front-end loaders, dozers, and scrap- 
ers will then follow. 



Table 2.-Dump-point accident data by equipment type, 


1983-87 




Equipment Accidents 


Fatalities 


Lost-workday 
accidents 


Lost 
workdays 


Haulage trucks 82 

Front-end loaders 6 


7 
2 
2 



61 
1 

7 
3 


4,282 
15 


Dozers 11 

Scrapers 4 


140 
384 



ANALYSIS OF DUMP-POINT ACCIDENTS INVOLVING HAULAGE TRUCKS 



GENERAL 

The ADA data base contained 82 dump-point accident 
narratives involving haulage trucks for the 1983-87 period. 
All original reports pertaining to the 82 accidents were 
reviewed. Two types of reports were available, full in- 
vestigative accident reports prepared by MSHA personnel 
and one-page MSHA Report Form 7000- 1-Mine Accident, 
Injury, and Illness reports completed and sent to MSHA 
by mine operators pursuant 30 CFR 50. These reports 
were requested to supplement data acquired through the 



ADA data base. The full investigative reports provided 
detailed information about the accidents, the causes of the 
accidents, and recommended procedures to be taken to 
prevent their recurrence. These full investigative reports 
were extremely beneficial in analysis of the dump-point 
accidents, however, they were only available for 26 of the 
accidents or 32 pet of the total. The remaining 56 acci- 
dents could only be analyzed by use of the one-page 7000- 
1 forms, which often did not provide enough data to 
identify accurately the causes of the accidents. 



80 pet 




5.7 pet 



KEY 



Haulage trucks 



Dozers 



Front— end loaders 



3.8 pet [^\^| Scrapers 



10.5 pet 
Figure 1 .-Percentage of dump-point accidents by equipment type. 





100 




90 


_l 

< 


80 


h- 




o 




I— 


70 


U_ 




O 


60 


UJ 




O 


50 


< 




I— 




V 




LU 


40 


o 




UJ 


30 


Q_ 






20 




10 









Haulage 
trucks 



Dozers Front-end Scrapers 

loaders 



KEY 



Fatalities 



Lost workdays 



EQUIPMENT TYPE 

Figure 2.-Percentage of dump-point fatalities and lost workdays by equipment type. 



Industry Affected 

A percentage breakdown of dump-point accidents by 
mineral industry is provided in figure 3. Combining sand 
and gravel operations and crushed stone operations, ag- 
gregate producers as a group are responsible for 55 pet of 
all accidents. The remaining dump-point accidents pre- 
dominantly occurred in the coal industry. 

Table 3 provides a breakdown of dump-point accidents 
by specific commodity for each mineral industry. The 
occurrence of the majority of dump-point accidents within 
a few mineral industries and specific commodities is sig- 
nificant. It suggests that certain material parameters or 
procedural activities occur in the crushed stone and coal 
industries that do not occur with frequency in the other 
mineral industries. Identification of these differences will 
aid in development of methods to reduce dump-point 
accidents. 

Table 3.-Dump-point accidents involving a haulage 
truck, by commodity 

Industry and commodity Accidents 

Crushed stone: 

Limestone 25 

Granite 4 

Traprock 4 

Miscellaneous stone 4 

Caliche 1 

Coal: Bituminous 25 

Metal: 

Copper 3 

Gold 2 

Iron 1 

Lead 1 

Silver 1 

Sand and gravel 7 

Other: 

Milled products: Cement 2 

Nonmetal: 

Clay 1 

Talc 1 

Dump-Point Structures 

Table 4 lists the number of dump-point accidents by 
industry and type of structure involved (see "Definitions" 



section). It was possible to determine the type of structure 
involved in 84 pet of the dump-point accidents analyzed. 
In metal-nonmetal mining operations, stockpiling activities 
accounted for the majority of dump-point accidents, with 
53 pet of the known total. This highlights the potential 
hazards of temporary structures that by their nature have 
a high amount of mobile equipment activity; this activity 
occurring at the top of the pile where dumping takes place 
and at the toe of the pile where some sort of loading 
procedure takes place. 

Crushed stone stockpiles were responsible for the sin- 
gle greatest amount of accidents-32 pet of the total. This 
results from the large amount of stockpiling activity asso- 
ciated with crushed stone operations. In the coal indus- 
try, waste dumps and spoil piles were responsible for the 
greatest percentage of accidents, whereas stockpile- 
associated accidents only occurred twice. 

Dump-Point Construction Materials 

Specific material parameters were not available for the 
dump-point structures, however, generalized categories of 
construction materials could be determined (table 5). Of 
the 52 accidents in which it was possible to determine the 
dump-point material, overburden, mine run (blasted 
stone), and screened stone were involved in the most 
accidents. 

Overburden was involved in the majority of the known 
cases (30 pet) and in both coal and metal-nonmetal mining 
operations. Overburden consistency can vary widely from 
location to location and can be an unpredictable material. 
Overburden is normally associated with permanent waste 
structures such as waste dumps or spoil piles. 

Mine run rock or blasted rock awaiting crushing was 
involved in 19 pet of the known cases, and occurred ex- 
clusively in metal-nonmetal mining operations. Screened 
stone was involved in 17 pet of the known cases and oc- 
curred exclusively in the crushed stone or aggregate in- 
dustry. Both mine run rock and crushed stone are asso- 
ciated with stockpile structures. The remainder of the 
known materials are distributed as shown in table 5. 



Table 4.-Structures involved in dump-point accidents, 1983-87 



Industry 


Stockpile 


Waste 
dump 


Surge 
pile 


Spoil 
pile 


Other 


Unknown 


Total 


Crushed stone . . . 


26 


6 


3 








3 


38 


Coal 


2 


6 





7 


4 


6 


25 


Metal 


3 


2 








1 


2 


8 


Sand and gravel . . 


4 


1 











2 


7 


Other 


1 


3 














4 


Total 


36 


18 


3 


7 


5 


13 


82 



46 pet 




KEY 

Crushed stone 
Coal 



Yff\ Metal 



Sand and gravel 



4 pet 



23 otner 



9 pet 



10 pet 
Figure 3.-Percentage of dump-point accidents involving a haulage truck, by industry. 



Table 5.-Dump-point construction materials involved 
in haulage truck accidents, by industry 

Material Coal Metal-nonmetal 

Unknown 10 20 

Overburden 11 5 

Mine run 10 

Screened stone .... 9 

Waste rock 3 3 

Fines, dust 3 

Sand 3 

Lime 2 

Coal 1 

Gravel 1 

Green shale __0 1 

Total 25 57 

Equipment Specifications 

The distribution of haulage trucks involved in dump- 
point accidents is shown in figure 4, by capacity. As can 
be seen, the majority of the dump-point accidents involved 
relatively smaller haul units in the 20- to 85-st-capacity 
range. It is felt (although unconfirmed) that this size 
distribution would correlate closely to the average haulage 
truck size distributions found in the industries analyzed. 



OPERATOR-RELATED FACTORS 
Age 

The age of operators involved in dump-point accidents 
varied from 19 to 62. The percentage of total dump-point 
accidents by age group is shown in figure 5. The line with 
the star markers represents the age of operators involved 
in the dump-point accidents. 

The age distribution of operators involved in dump- 
point accidents closely matches the normal age distribution 
for mine truck drivers. It therefore appears that there is 
no relationship between the age of a haulage truck oper- 
ator and the potential that he or she will be involved in a 
dump-point accident. 

Job Experience 

A significant portion of dump-point accidents involve 
operators with very little to no experience operating a 
haulage truck. The number of dump-point accidents in- 
volving a haulage truck by years of job experience is shown 
in figure 6. 



CO 

I— 

Ld 
Q 

O 
O 
< 

l_i_ 

o 
a: 

Ld 

m 



25 



20 



15 



10 - 



Coal 



Metal— nonmetal 



K3 B B B 



_B. 



n n 



Lk 



a. 



2 10 13 15 20 22 25 35 50 55 85 90 110 120 170 

CAPACITY, st 

Figure 4.-Number of haulage trucks involved in dump-point accidents, by capacity. 



< 

O 

h- 

L_ 

o 

LxJ 
O 
< 



Ld 
CJ 

a: 

Ld 

a. 



25 



20 



15 - 



10 - 




KEY 



■j,- Operators involved 
in dump-point 
accidents 



Normal age 
distribution for 
all truck 
operators 
(sample size= 
28.127) 



-B- 



15-20 21-23 24-26 27-29 30-34 35-39 40-49 ^>50 

AGE 
Figure 5.-Percentage of total dump-point accident* Involving a haulage truck, by age group. 



i— 

9 

o 
o 
< 

Ll. 

o 
a: 
m 



30 



25 - 



20 - 



15 - 



10 - 








<1 1 2 3 4 5 6 7 8 9 10 1 1 1 2 13 1 4 15 1 6 1 7 1 8 1 9 20 21 22 23 24 25 26 27 



YEARS OF EXPERIENCE DRIVING A HAULAGE TRUCK 

Figure 6.-Number of dump-point accidents involving a haulage truck, by years of job experience. 



The average amount of job experience for a haulage 
truck operator involved in a dump-point accident is 3.81 
years. However, 41 pet of all dump-point accidents oc- 
curred to an operator with less than 1 year of haulage 
truck experience. Of those accidents involving less than 
1 year of experience, 41 pet had less than 1 month expe- 
rience and 82 pet had less than 6 months of experience. 

It is obvious that lack of job experience is a significant 
contributing factor to the occurrence of a dump-point ac- 
cident. This suggests that experienced operators have 
learned to identify and avoid potentially unsafe areas for 
dumping or have learned operating techniques that tend to 
prevent dump-point accidents. Increased emphasis on 
hazards associated with stockpiles and waste dumps during 
mandatory miner training would have a significant impact 
on the reduction of dump-point accidents. The fact that 
inexperience is a major contributing factor suggests that 
human error (administrative and operator) is responsible 
for a majority of the accidents. 

Mine Experience 

The number of accidents per year of total mine experi- 
ence is shown in table 6. The average amount of total 
mine experience for an operator involved in a dump-point 
accident is 7.3 years or 3.5 years higher than the average 
specific job experience. This suggests that experience 
gained in mining activities other than driving a haulage 



truck has little impact on the operator's ability to safely 
operate a haulage truck when he or she is eventually as- 
signed to that task. This could also imply a supervisor's 
incorrect assumption that an experienced miner has the 
required training or experience to perform a new task even 
when he or she has not performed that specific task. 

Drug and Alcohol Abuse 

Drug testing is rarely performed in the mining industry 
after an accident has occurred. The exception to this is 
when an autopsy is performed after a fatal accident. Of 
the 82 haulage truck accidents reviewed in this study, only 
five reports made mention of drugs or alcohol. Two of 
these reports specifically stated that drugs were not a con- 
tributing factor. Therefore, only three accidents occurred 
where drugs could be considered as a contributing factor 
and two of these involved fatalities. Although the use of 
drugs and alcohol is often mentioned as a potential con- 
tributing factor in accidents, there is very little evidence 
to substantiate this for dump-point accidents. The fact 
that two of the seven fatalities involved alcohol could in- 
dicate the potential for a more serious accident to occur 
while under the influence or just that more thorough test- 
ing is performed when a fatality occurs. Not enough infor- 
mation was available to determine the contribution of 
drugs and/or alcohol to dump-point accidents. 



10 



Table 6.-Dump-point accidents Involving a haulage truck, by years of mine experience 

Experience Accidents Experience Accidents 



. 
<1 

1 . 

2 . 

3 . 

4 . 

5 . 

6 . 

7 . 

8 . 

9 . 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 



4 

13 

8 

8 

7 
3 
4 
3 
2 
3 
3 
5 
3 
1 
1 
1 
3 
1 
1 
1 




20 
21 
22 
23 
24 
25 
26 
27 
28 
29 
30 
31 
32 
33 
34 
35 
36 
37 
38 
39 



Total 



82 



Seatbelt Use 

In a rollover accident, seatbelts can be instrumental in 
the prevention of serious injury or death. The 82 haulage 
truck accidents were reviewed to determine if seatbelts or 
the lack of seatbelts were a contributing factor to the 
amount of injury sustained by the operator. Only 14 ac- 
cident reports mentioned the use or non-use of seatbelts 
(table 7). Because of the lack of reporting concerning 
seatbelts, it is not possible to discern if the majority of 
lost-work-time injuries could have been reduced in severity 
or eliminated by the use of seatbelts. In four of seven 
total fatalities, however, specific mention was made that 
the operator was not wearing a seatbelt. A reasonable 
assumption can be made that at least some of the fatalities 
could have been prevented had seatbelts been worn. The 
importance of wearing seatbelts should be emphasized to 
all mobile equipment operators. Federal regulations cur- 
rently mandate that seatbelts be provided and worn in 
haulage trucks (30 CFR 56.14131 and 30 CFR 57.14131). 

Table 7.-Summary of data corresponding 
to use of seatbelts 



Accidents involving- 
Fatalities 

Permanent disability .... 

Lost workdays 

No time lost 

Unknown 



PRIMARY ACCIDENT CAUSES 

The 26 full investigative reports provided a complete 
explanation of the primary accident causes and contrib- 
uting factors. After a thorough review of these reports, it 
became evident that a relatively small group of causes 
were responsible for the majority of the accidents. Often 
there were several causes that when combined resulted in 



Seatbelts- 


Worn 


Not worn 





4 





1 


2 


5 


1 








1 



the occurrence of a dump-point accident. A pattern of 
several factors combining to cause a dump-point accident 
emerged. 

For the remaining 56 accidents, where a full investi- 
gative report was not available, the one-page 7000-1 form 
accident reports were analyzed. Twenty-three of these 
reports provided enough information to determine the 
primary accident cause, however, the contributing factors 
often could not be determined. The remaining 33 reports 
did not provide enough detail to determine accurately the 
primary cause for the accident although in some cases 
contributing factors could be identified. 

A summary of the primary accident causes is shown in 
figure 7. The majority of the accidents occurred as a 
result of administrative or operator error (loading out at 
the toe, backing over edge, etc.) while only eight of the 
accidents occurred because of an unexplained slope failure. 
This highlights the importance of addressing dump-point 
accidents from an administrative and operational viewpoint 
as well as the study of specific parameters effecting slope 
stability. 

Table 8 provides a breakdown of those factors that 
contributed to the occurrence of an accident. The nine 
contributing factors identified through analysis of the ac- 
cident reports are listed, along with the number of times 
a specific factor could be identified as contributing to the 
primary accident cause. Several of the contributing fac- 
tors (i.e., dumpbed position, truck motion, truck orienta- 
tion) provide information that can aid in modeling of the 
accidents. 

The information in table 8 is not complete and does not 
provide a thorough representation of the contributing 
factors for all of the primary accident causes listed. Again, 
this is because of the lack of detail provided on many of 
the accident reports. It does, however, present the best 
information that is available and does help in development 
of an understanding of dump-point accidents. 



11 



Ld 

< 
CJ 



LU 

g 

o 
o 
< 

>- 

< 

LT 
Q_ 



Loading out at toe 

Backed over edge 

Slope failure 

Backed through berm 
Dumped incorrect area 

Mechanical 

Other 

Undetermined 




10 



15 



20 



25 



30 



35 



NUMBER OF ACCIDENTS 



Figure 7.-Primary dump-point accident causes involving haulage trucks. 



Table 8.-Primary accident causes and contributing factors for 82 dump-point accidents 

Loading Backing Slope Backing Dumping 
Contributing factors out at over failure through incorrect Mechanical Other Undetermined Total 
the toe edge berm area 

Accidents 1 17 12 8 7 3 1 1 33 82 

No berm 13 11 2 1 1 2 30 

Truck orientation: 

Right 4 3 1 2 3 13 

Left 1 1 1 1 4 

Substance abuse 1 1 1 3 

No lighting 1 1 1 3 

Dumpbed position: 

Up 2 2 5 9 

Down 14 6 5 6 1 1 10 43 

Slope failure 13 1 8 1 1 24 48 

Truck motion: 

Moving 12 12 7 2 1 9 43 

Stopped 5 6 5 16 

Dumping incorrect area ..1 00 3 4 

Construction method .... 17 12 8 7 3 1 1 33 82 

Total accidents by primary accident cause; remaining entries in each column are number of times another factor could be identified as 
a contributing cause. 



12 



Loading Out at the Toe 

Loading out at the toe refers to the procedure of re- 
moving material from the base or toe of a stockpile, often 
with a front-end loader. This material is generally loaded 
into trucks for shipping or is fed directly into crushers or 
feeders for further processing. This is a normal procedure 
for most mining operations and other than placing feeders 
under the stockpile (often not applicable) is the only meth- 
od available for reclaiming stockpiled materials. The 
method is safe but does result in formation of vertical or 
near vertical faces on the leading edge of the stockpile. 
The formation of a stockpile face with an angle steeper 
than the normal angle of repose results in a slope with a 
reduced bearing capacity. This normally does not present 
a problem to the loader operator at the base of the pile, 
who continually watches for collapse of the steepened face 
while it is being reclaimed. However, any mobile equip- 
ment or personnel at or near the crest of the stockpile are 
in danger of being involved in a slope failure and any re- 
sulting accidents. In addition, truck drivers and other 
personnel on foot at the base of the pile, for instance 
drivers who may be walking around behind their highway 
truck while it is being loaded, are in danger of being en- 
gulfed during a slope failure. 

Of the 49 accidents for which a specific cause could be 
determined, 17 occurred when a haulage truck backed to 
the top edge of a pile where the toe had been removed. 
In 14 of these accidents, the weight of the truck caused the 
oversteepened slope to fail with the resultant falling of the 
truck over the edge. In three other accidents, undercutting 
of the pile resulted in removal of the berm at the top of 
the pile. In these three instances, the truck operator sim- 
ply backed over the edge of the pile. 

The problem associated with dumping over the edge of 
a pile while concurrently loading out at the toe predom- 
inantly exists in the metal-nonmetal industry. Fifteen of 
the seventeen accidents occurred in the metal-nonmetal 
industry, seven on crushed and sized stone stockpiles, 
seven on quarry rock stockpiled for crusher feed, and one 
on an unknown stockpile. The two accidents that occurred 
in coal both involved overburden, one occurred when a 
berm had been removed because of reclamation activities 
on a spoil pile. Significantly, four of the seven haulage- 
truck-related dump-point fatalities involved an accident 
where the toe of a stockpile had been removed, three 
occurring in metal-nonmetal and one in coal. 

Thirteen of seventeen accidents occurred where no 
berm was in place. This is important in that it could allow 
a truck to dump very close to the edge of an already weak- 
ened slope thereby substantially increasing the probability 
of a slope failure. Use of berms, however, would not 
adequately insure the prevention of this type of accident. 
In four of the accidents, berms were in place and being 
utilized. In these four cases the undercutting that took 
place resulted in slopes so weakened that the slopes in- 
cluding berms failed when the truck backed into place. 
The use of berms in these instances actually resulted in a 



false sense of security for the operator who assumed the 
berm signified a stable slope. 

A method of stockpiling that concurrently utilizes end- 
dumping techniques while reclaiming from the toe is inher- 
ently dangerous and should be avoided. The mine super- 
visor should insure that these two activities do not occur 
concurrently at the same location, and the truck operator 
should insure that he or she is not dumping at a point that 
has been steepened by reclaiming activities. 

Backing Over Edge 

Backing over the edge of a pile (no slope failure) was 
responsible for 12 of the dump-point accidents. In this 
type of accident, the truck operators do not judge the 
distance to the edge of the pile correctly and simply back 
over the edge. In each accident (except one where it was 
not documented), a berm or spotting device had not been 
provided. Thus although the operator was at fault for 
backing too far, had a berm or spotting device been pro- 
vided, the majority of these accidents could have been 
prevented. The major contributing factor in this case is 
therefore administrative for not providing a spotting de- 
vice or berm as required by law. Inadequate lighting con- 
tributed to one of the accidents when the operator could 
not clearly see the edge of the slope. It should be noted 
that after discussions with MSHA personnel it is felt that 
missing or insufficient mirrors and poor brakes also con- 
tributed in some part to these accidents, however this 
cannot be substantiated. 

Slope Failure 

Slope failure refers to any soil movement that could 
contribute to or be the primary cause of a dump-point 
accident. The range of failure mechanisms can vary from 
the settlement of unconsolidated material under one wheel, 
resulting in the truck tipping on its side, to a massive 
failure where a bank or slope completely collapses under 
the weight of a truck. 

Slope failures were involved in 58 pet of the total dump- 
point accidents reported. A summary of the contribution 
of slope failures to dump-point accidents is provided in 
table 9. In 25 of the accidents it was not possible to deter- 
mine the type or size of the failure, or if the failure was 
the primary cause for the accident or only a contributing 
factor. A slope failure was identified as a contributing 
factor in the occurrence of 15 accidents and was the pri- 
mary accident cause for 8 accidents. 

Of the eight accidents in which a slope failure was the 
primary accident cause, only one was substantiated by a 
full investigative report. In this case, uncompacted sand 
sloughed away under the rear wheels of the truck causing 
it to turn on its side. In the remaining seven accidents the 
documentation was relatively poor, which prevented a 
thorough characterization of the failure, however, they all 
occurred in the coal industry. All seven of these accidents 
occurred on dump or fill structures where loading out at 



13 



the toe would not normally occur. This would tend to 
substantiate the occurrence of the slope failure due to 
weak geomechanical properties other than to other pri- 
mary accident causes. Of these seven accidents, four oc- 
curred on spoil piles consisting of overburden, two oc- 
curred on unknown materials, and one occurred on a rock 
dump. 

Table 9.-Summary of haulage truck dump-point 
accidents involving slope failure 

Primary cause Accidents 

Loading out at the toe 13 

Backed through berm 1 

Dumped incorrect area 1 

Undetermined 25 

Slope failure 8 

Backing Through Berm 

Seven of the dump-point accidents occurred when the 
vehicle operator backed through, or in one case over, an 
existing berm. There is confusion as to the utilization of 
berms in the prevention of dump-point accidents. A nor- 
mal rule of thumb states that berm height should be equal 
to the mid-axle height of the largest vehicle using the 
dump site (for haulroads this is mandatory under 56.9300 
and 57.9300). But what is the purpose of a berm at a 
dump point? To provide a visual indication of where the 
truck should be stopped? To provide a "feeling" of the 
berm as the rear tires contact it? To impede the motion 
of a truck that contacts it at some moderate speed? Sure- 
ly, the true purpose probably lies somewhere in between, 
however, the equipment operator cannot assume that a 
berm will impede vehicle motion or that it should be used 
as an aid in stopping the vehicle. A vehicle operator 
should utilize a berm for spotting only. Had this been 
done in these seven cases, most of the accidents could have 
been avoided. 

Lack of adequate lighting contributed to the occurrence 
of one accident by not allowing the operator to spot the 
berm and thus slow in time. One of the accidents oc- 
curred when an apparently insufficient berm failed along 
with part of the slope when the truck contacted it (the 
speed of the vehicle when it contacted the berm is un- 
known). The relative strength of berms is dependent on 
their size, shape, construction materials, and type of struc- 
ture on which they are located. This information has been 
determined for haulroads, 3 and where possible should be 
applied to dump points. 



Stecklein, G. L., and J. Labra. Haulroad Berm and Guardrail 
Design Study and Demonstration. Volume I (contract H0282028, SW 
Res. Inst.). BuMines OFR 188-82, 1981, 186 pp.; NTIS PB 83-137091. 



Dumping Incorrect Area 

Three of the dump-point accidents occurred when the 
haulage truck operator failed to dump where specified by 
supervisors. In two of these accidents, the operators 
backed over the edge of a pile where no berms were pro- 
vided. In both cases, the operators had been instructed 
to dump in nearby areas where bulldozers were being used 
to push the material over the edge of the pile. It is un- 
certain why the operators failed to dump where instructed, 
although it was alluded in the reports that they may have 
been trying to assist the dozer operators by dumping di- 
rectly over the edge. In one of these instances the oper- 
ator had worked two 8-hour shifts with only 8 hours off 
between shifts. In this case, a fatality occurred and the 
autopsy revealed that the operator was legally drunk. 

The third case involved an operator dumping near the 
middle of the pile instead of the end where directed. The 
operator was backing near the edge of the pile when the 
right rear tire began sinking in the material causing the 
truck to tip on its side. Although closer supervision may 
have prevented these accidents, the primary responsibility 
cases belongs to the operators. 

Mechanical 

A mechanical failure was responsible for only one 
dump-point accident. In this particular case, the parking 
brakes failed to hold while the operator was raising the 
dumpbed. This allowed the truck to roll over the edge of 
the dump point where no berm had been provided. In 
this case a berm probably would have prevented the acci- 
dent. Although mechanical failures are common causes of 
powered haulage accidents, it cannot be shown that they 
are a frequent factor in dump-point accidents. 

Undetermined 

For 40 pet of the dump-point accidents analyzed, it was 
not possible to determine the primary accident cause. The 
accident descriptions provided by the mine operators in 
these cases were poorly written and often consisted of only 
one fragmented sentence. It could be reasonably assumed 
that these accidents would distribute evenly as a ratio to 
the known accident causes. However, in order to maintain 
a high degree of integrity and accuracy in this study, no 
attempt was made to interpret these reports or distribute 
them by ratio into other accident categories. 

As shown in table 8, however, although the primary 
accident cause could not be determined it was often pos- 
sible to identify contributing factors. The most significant 
contributing factor alluded in the reports was that some 
sort of slope failure occurred, although the lack of detailed 
descriptions precluded the characterization of the failures. 



14 



It is unclear whether the problem of inadequate and 
poorly written reports can be addressed and corrected by 
MSHA, however, such reports present problems to anyone 
trying to complete a detailed analysis of safety problems 
and health trends in the mining industry. 

CONTRIBUTING FACTORS 

Construction Method 

In every dump-point accident analyzed, the method of 
stockpile construction consisted of end dumping, where the 
haulage truck actually dumped the load directly over the 
crest of the pile. Elimination of this type of dumping 
procedure would effectively eliminate the majority of 
dump-point accidents. A preferred procedure would con- 
sist of the haulage truck dumping the load back from the 
crest of the pile where it would then be pushed over the 
edge by dozer or loader. This procedure would also al- 
low for maintenance of berms in the dump areas. It is 
understood that this is not always a practical alternative 
for a mine operator in which case other precautions should 
be taken when utilizing end-dumping techniques. These 
would include maintaining adequate berms, not loading out 
at the toe where stockpiling activities are going to take 
place, maintaining a well-trained and informed workforce, 
and performing regular inspections of dump points for any 
potential hazards or unsafe working procedures. 

Truck Orientation 

In 17 accidents, truck orientation was specifically men- 
tioned as a contributing factor. In this type of accident, 
the truck is not backed perpendicular to the slope edge, 
allowing one tire to reach the edge before the other. Most 
often this occurs on the side of the truck opposite the 
driver's compartment. This apparently occurs as a result 
of the operator's inability to accurately judge distance on 
this far side. Backing at an angle to the slope edge con- 
tributed to 5 of the 12 backover accidents. In these 



accidents, no berms were provided and the operator's in- 
ability to judge the distances correctly allowed one tire to 
slip off the edge resulting in the fall of the remainder of 
the truck. Another potential hazard associated with back- 
ing at an angle is the uneven weight distribution imposed 
on the slope edge while the load is being dumped. If 
through misjudgment of distance the operator does not 
slow sufficiently before one tire contacts a berm, failure of 
the berm could occur, resulting in the backing of the truck 
over the edge. 

Dumpbed Position 

The position of the dumpbed could have an effect on 
slope stability. As the dumpbed is raised into the dump- 
ing position, the weight distribution is increased on the 
rear wheels resulting in increased bearing pressure on the 
slope. This can be magnified if the operator rocks the bed 
to free sticky material. Information on the position of the 
dumpbed could be determined in 38 accidents. In 29 ac- 
cidents, the dumpbed was in the down position and in 9 
it was raising or in the up position. Because of poor docu- 
mentation, it was not readily apparent if the bed being in 
the raised position had an influence on the occurrence of 
slope failures. 

Truck Motion 

It was possible to infer the motion of the haulage truck 
in 59 of the dump-point accidents. In 73 pet of these acci- 
dents, the truck was in motion and moving backwards to- 
ward the slope edge. This is of particular interest in those 
accidents involving some degree of slope failure. As the 
truck applies its brakes to stop near the dump point, a 
horizontal force is imposed on the slope in addition to the 
normal vertical force imposed by the weight of the truck. 
This additional horizontal force substantially increases the 
potential of a slope failure. The result of horizontal force 
loadings on dump points is being carefully analyzed in 
modeling studies of slope failures. 



ANALYSIS OF DUMP-POINT ACCIDENTS INVOLVING FRONT-END LOADERS 



Front-end loaders were responsible for 5.7 pet of all 
dump-point accidents analyzed. This equates to six ac- 
cidents for the 5-year period studied. Of these six acci- 
dents, two resulted in a fatality. A summary of front-end 
loader accidents by specific commodity and severity is 
shown in table 10. All of the accidents occurred in the 
aggregate industry, where front-end loaders are used heavi- 
ly in the construction of stockpiles. A full investigative 
report (portions missing) was available for one of the 
accidents involving a fatality, the remaining five accidents 
were analyzed utilizing ADA accident narratives generated 
from the one-page, 7000-1 form accident reports. 

Both fatalities occurred when the operator was thrown 
from the loader and pinned under the machine. In one 
instance, an equipment fall occurred as a result of the 



operation of the loader near the crest of a slope that had 
been weakened by loading out at the toe. In the other 
fatality, a slope failure occurred as the operator backed the 
right rear tire over the edge of the pile. In this accident 
the shape of the slope could not be determined. 

For the four nonfatal accidents, the primary accident 
cause could not be determined, although some contributing 
factors could be identified including lack of berms, slope 
failure, and operator error (backing over edge). It appears 
that front-end loader accidents are similar in nature and 
cause to haulage truck accidents and could be reduced by 
techniques implemented to reduce haulage truck accidents. 
Front-end loaders differ from haulage trucks in that they 
are used for the construction of berms at the crest of 
stockpiles as well as for hauling material for stockpile 



15 



construction. They can spend considerably more time near 
the crest of a stockpile and in potentially more hazardous 
positions. It is therefore important that the operator 



remain attentive to potential hazards especially during 
the construction of berms and not become complacent 
with the work environment. 



Table 1 0.-Summary of occurrence and severity of dump-point accidents involving front-end loaders 



Industry 



Accidents 



Fatalities 



Lost-workday 
accidents 



Lost 
workdays 



Sand and gravel . . 
Crushed limestone 
Crushed granite . . 



15 





ANALYSIS OF DUMP-POINT ACCIDENTS INVOLVING DOZERS 



Dozers were responsible for 10.5 pet of all dump-point 
accidents. This equates to 11 accidents for the 5-year 
period studied. Of these 11 accidents, 2 resulted in a 
fatality. A summary of dozer accidents by specific com- 
modity and severity is given in table 11. The coal industry 
had both the greatest frequency and severity of dump- 
point-related dozer accidents. The reason for the concen- 
tration of accidents within the coal industry is uncertain, 
although it seems reasonable that with the amount of 
overburden removal and reclamation activities prevalent in 
coal that simply more dozers are used. 

ADA accident narratives were used in the analysis of all 
the dozer accidents, including both fatalities. Although 
detail in the ADA narratives is lacking, dozer accidents 
appear to fall into two general categories. The first cat- 
egory involves the operator backing the dozer over the 
edge of the pile either through inattentiveness or the result 
of mechanical problems. The second category involves a 
slope failure although it is not apparent if there may have 
been other contributing factors such as loading out at the 
toe. 

Five accidents occurred when the dozer simply went 
over the edge of the pile. In one case, the throttle stuck 
and forced the dozer over the bank. In another, the oper- 
ator momentarily lost control and the machine rolled back 
over a dump. In three accidents, the operators simply 



backed over the edge, in one case overturning the dozer 
and in the other two simply jarring the operator's back. 

Slope failures occurred in five of the dozer accidents 
including one of the fatalities. In this fatality, material 
collapsed during a reclamation operation allowing the 
dozer to slide into 15 ft of water. It is unclear in this 
accident if the dozer was operating at the top of the pile 
or along the front slope. In the remaining slope-failure- 
related accidents, it appears that the stockpiled material 
collapsed under the weight of the dozer while the unit was 
close to and running parallel to the top edge of the pile. 
There is not enough information available to accurately 
characterize these slope failures or determine what could 
have been done to prevent them. The primary cause for 
the second dozer fatality is unclear, it was simply stated in 
the accident narrative that the dozer fell into a void on a 
coal stockpile, probably formed by a pan feeder beneath 
the pile. 

Only four of the accidents resulted in the dozer over- 
turning. In the others, it appears they simply slid uncon- 
trolled for some unknown distance. Dozers operate both 
at the crest of structures and often on the slopes of a 
structure. Because of this varied usage and the poor docu- 
mentation of the accidents, it is difficult to determine 
specific operating techniques that might eliminate the 
occurrence of dozer-related slope failures. 



Table 1 1 .-Summary of occurrence and severity of dump-point accidents involving dozers 

Industry 



Coal 

Iron 

Silver 

Sand and gravel . . 
Crushed limestone 
Clay 



Accidents 


Fatalities 


Lost-workday 


Lost 






accidents 


workdays 


6 


2 


4 


106 







1 


3 







1 


16 







1 


15 

























16 



ANALYSIS OF DUMP-POINT ACCIDENTS INVOLVING SCRAPERS 



Only four (slightly more than 1 pet) of all scraper acci- 
dents occurred because of the fall of the scraper over a 
dump-point structure. None of the scraper accidents in- 
volving dump points resulted in a fatality although the 
number of lost workdays per LWA was extremely high, an 
average of 128 days per accident. 

The documentation for these accidents was poor with 
no full investigative reports available. Two of the accidents 
occurred in the coal industry on spoil piles. In both in- 
stances, it appears the unit was dumping near the edge of 



the stockpile when it slid over the edge. The remaining 
two accidents occurred in the crushed limestone industry. 
The stockpile material for these accidents was not listed, 
however, as in coal most scraper operations involve the 
movement of overburden. In both of the limestone indus- 
try accidents it was stated that the scraper was driven too 
close to the edge of the pile. It is unclear in these cases 
whether a slope failure occurred or if the operator simply 
drove over the edge. 



MSHA REGULATIONS PERTAINING TO DUMP-POINT SAFETY 



MSHA has the responsibility for the development and 
enforcement of Federal regulations relating to the pro- 
motion of safety and health and the prevention of acci- 
dents in the metal-nonmetal and coal industries. The 
generation and development of most safety-related regu- 
lations takes place over time in response to specific haz- 
ards occurring in the minerals industry. The regulations in 
effect are the accumulation of many years of effort and 
evolution by MSHA to reduce the severity and frequency 
of mining accidents. These regulations continue to evolve 
and change to reflect changing mining methods and tech- 
nologies. A review of those regulations that have been 
generated in response to the specific hazards associated 
with dump points provides a more thorough understanding 
of dump-point accidents, the environment in which they 
occur, and approaches taken to control them. Regulations 
pertaining to the construction and use of stockpiles and 
dump points are included in the CFR, Title 30-Mineral 
Resources, parts 56, 57, and 77. Excerpts of those regu- 
lations specifically directed towards the operation of mo- 
bile mining equipment on stockpiles and waste dumps are 



contained in the appendix, as well as additional regulations 
indirectly related to equipment operation. 

A review of the regulations pertaining to the construc- 
tion and use of stockpiles and waste dumps highlights the 
difficulties encountered in regulating the minerals industry. 
The minerals industry is extremely diverse. Its operations 
vary greatly, depending upon the commodity mined and 
the specific mining methods and equipment used. The 
parameters that can vary in regard to the construction 
and use of stockpiles and waste dumps include the type 
of material used, the construction method, the pile size, 
the type and size of the mobile equipment, the effects of 
weather, the effects of reclaiming, and many others. The 
varying nature and complexity of the parameters affecting 
stockpile and waste dump construction is reflected in the 
generalized and somewhat vague wording that is used in 
the regulations. This may also reflect a basic lack of in- 
formation about the parameters that affect stockpile and 
waste dump stability, resulting in the inability to generate 
more specific guidelines and regulations. 



SUMMARY 



Failures at mine dump points are particularly dangerous 
because of the height of the slopes and size of the mobile 
equipment involved. When slope instability or operational 
errors result in a piece of mobile equipment tumbling over 
the edge of a stock pile or waste dump the results can be 
disastrous. In most cases, the accidents result in lost work 
time or death. Approximately 16 accidents resulting in lost 
work time or death occur every year. Although this is a 
relatively small number, dump-point accidents have a much 
higher likelihood of resulting in a fatality or significant 
lost-work-time injury than most other surface mining acci- 
dents. Dump-point accidents occur in all of the major 
mineral industries including coal, metal, nonmetal, crushed 
stone, and sand and gravel; however, they predominantly 
occur in the crushed stone and coal industries. 

After a thorough review of the 82 dump-point accidents, 
it became evident that a relatively small group of causes 



were responsible for the majority of the accidents. The 
accidents were primarily due to administrative or opera- 
tor error (loading out at the toe, backing over edge, etc.) 
while only a small percentage of accidents involved unex- 
plainable slope failures. The majority of the accidents 
could have been avoided had there been a better under- 
standing of the potential hazards associated with the oper- 
ation of mobile equipment on stockpiles and waste dumps 
and the interrelationship between vehicle operation and 
slope stability. 

Most of the accidents involved haulage trucks although 
dozers, front-end loaders, and scrapers accidents also 
occurred. A better understanding of the potential hazards 
associated with stockpiles and waste dumps should allow 
mine operators to minimize the occurrence of this type of 
accident. 



17 



BIBLIOGRAPHY 



Bowers, E. T. Using ADA (Accident Data Analysis) in Mine Safety 
Research. BuMines OFR 72-86, 1986, 111 pp. 

Butani, S. J., and A M. Bartholomew. Characterization of the 1986 
Coal Mining Workforce. BuMines IC 9192, 1986, 76 pp. 

. Characterization of the 1986 Metal and Nonmetal Mining 

Workforce. BuMines IC 9193, 1986, 69 pp. 

U.S. Code of Federal Regulations. Title 30-Mineral Resources; 
Chapter I-Mine Safety and Health Administration, Department of 
Labor; Subchapter M-Accidents, Injuries, Illnesses, Employment, and 
Production in Mines; Part 50-Notification, Investigation, Reports and 
Records of Accidents, Injuries, Illnesses, Employment, and Coal 
Production in Mines. 

. Title 30-Mineral Resources; Chapter I-Mine Safety and 

Health Administration, Department of Labor; Subchapter N-Metal and 
Nonmetal Mine Safety and Health; Part 56-Safety and Health 
Standards-Surface Metal and Nonmetal Mines. 



U.S. Code of Federal Regulations. Title 30-Mineral Resources; 
Chapter I-Mine Safety and Health Administration, Department of 
Labor; Subchapter N-Metal and Nonmetal Mine Safety and Health; 
Part 57-Safety and Health Standards-Underground Metal and 
Nonmetal Mines. 

. Title 30-Mineral Resources; Chapter I-Mine Safety and 

Health Administration, Department of Labor; Subchapter O-Coal Mine 
Safety and Health; Part 77-Mandatory Safety Standards-Surface Coal 
Mines and Surface Work Areas of Underground Coal Mines. 

U.S. Department of Labor, Mine Safety and Health Administration. 
Fatalgram series. 



18 



APPENDIX.-CODE OF FEDERAL REGULATIONS EXCERPTS 

PERTAINING TO OPERATION OF MOBILE EQUIPMENT 

ON STOCKPILES AND WASTE DUMPS 



The following excerpts of Title 30— Mineral Resources 
pertain to operation of mobile equipment on stockpiles 
and waste dumps. In addition to the excerpts, other regu- 
lations within parts 56, 57, and 77 that are indirectly 
related to such operation are cited. Portions of Part 
48-Training and Retraining of Miners, are also included. 
The following regulations are subject to periodic revision. 
A MSHA representative should be contacted on a regular 
basis for changes. 

SAFETY AND HEALTH STANDARDS-SURFACE 
METAL AND NONMETAL MINES 

30 CFR 56.9101 Operating speeds and control of 
equipment. 

Operators of self-propelled mobile equipment shall 
maintain control of the equipment while it is in motion. 
Operating speeds shall be consistent with conditions of 
roadways, tracks, grades, clearance, visibility, and traffic, 
and the type of equipment used. 

30 CFR 56.9301 Dump site restraints. 

Berms, bumper blocks, safety hooks, or similar imped- 
ing devices shall be provided at dumping locations where 
there is a hazard of overtravel or overturning. 

30 CFR 56.9303 Construction of ramps and dumping 
facilities. 

Ramps and dumping facilities shall be designed and 
constructed of materials capable of supporting the loads 
to which they will be subjected. The ramps and dumping 
facilities shall provide width, clearance, and headroom 
to safely accommodate the mobile equipment using the 
facilities. 

30 CFR 56.9304 Unstable ground. 

(a) Dumping locations shall be visually inspected prior 
to work commencing and as ground conditions warrant. 

(b) Where there is evidence that the ground at a dump- 
ing location may fail to support the mobile equipment, 
loads shall be dumped a safe distance back from the edge 
of the unstable area of the bank. 

30 CFR 56.9305 Truck spotters. 

(a) If truck spotters are used, they shall be in the 
clear while trucks are backing into dumping position or 
dumping. 



(b) Spotters shall use signal lights to direct trucks where 
visibility is limited. 

(c) When a truck operator cannot clearly recognize the 
spotter's signals, the truck shall be stopped. 

30 CFR 56.9314 Trimming stockpile and muckpile faces. 

Stockpile and muckpile faces shall be trimmed to pre- 
vent hazards to persons. 

The following are regulations of part 56 that indirectly 
relate to stockpile construction and use, and regulations 
pertaining to aspects of stockpile construction not involving 
the use of mobile mining equipment. 



30 CFR 56.3130 
30 CFR 56.3200 
30 CFR 56.3401 
30 CFR 56.14100 

30 CFR 56.14130 

30 CFR 56.14131 
30 CFR 56.17001 
30 CFR 56.20001 



Wall, bank, and slope stability 

Correction of hazardous conditions 

Examination of ground conditions 

Safety defects, examination, correction 

and records 

Rollover protective structures and seat 

belts 

Seat belts for haulage trucks 

Illumination of surface working areas 

Intoxicating beverages and narcotics 



SAFETY AND HEALTH STANDARDS- 
UNDERGROUND METAL AND 
NONMETAL MINES 

Regulations for surface stockpiles and waste dumps at 
underground metal and nonmetal mining locations (30 
CFR 57) are identical to those in 30 CFR 56 for surface 
mines. 

MANDATORY SAFETY STANDARDS, SURFACE 

COAL MINES AND SURFACE WORK AREAS 

OF UNDERGROUND COAL MINES 

30 CFR 77.1605 Loading and haulage equipment; 
installations. 

(i) Ramps and dumps shall be of solid construction of 
ample width, have ample clearance and headroom, and be 
kept reasonably free of spillage. 

(1) Berms, bumper blocks, safety hooks, or similar 
means shall be provided to prevent overtravel and over- 
turning at dumping locations. 



19 



30 CFR 77.1607 Loading and haulage equipment; 
operation. 

(b) Mobile equipment operators shall have full control 
of the equipment while it is in motion. 

30 CFR 77.1608 Dumping facilities. 

(a) Dumping locations and haulage roads shall be kept 
reasonably free of water, debris, and spillage. 

(b) Where the ground at a dumping place may fail to 
support the weight of a loaded dump truck, trucks shall be 
dumped a safe distance back from the edge of the bank. 

(c) Adequate protection shall be provided at dumping 
locations where persons may be endangered by falling 
material. 

(d) Grizzlies, grates, and other sizing devices at dump 
and transfer points shall be anchored securely in place. 

(e) If truck spotters are used, they shall be well in the 
clear while trucks are backing into dumping position and 
dumping; lights shall be used at night to direct trucks. 



The following are regulations of part 77 that indirectly 
relate to stockpile construction and use, and regulations 
pertaining to aspects of stockpile construction not involving 
the use of mobile mining equipment. 



30 CFR 77.209 
30 CFR 77.214 
30 CFR 77.215 



30 CFR 77.403a 

30 CFR 77.404 

30 CFR 77.1000 
30 CFR 77.1600 
30 CFR 77.1606 



Surge and storage piles 
Refuse piles; general 
Refuse piles; construction requirements; 
identification; reporting requirements; 
certification; abandonment 
Mobile equipment; rollover protective 
structures 

Machinery and equipment; operation and 
maintenance 

Highwalls, pits and spoil banks, plans 
Loading and haulage; general 
Loading and haulage equipment; inspec- 
tion and maintenance 



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